Relative to SISO (the initials standing for “Single Input Single Output”) systems comprising a single transmit antenna and a single receive antenna, the advantage of SIMO/MIMO systems is, by virtue of the spatial diversity of the propagation channel, that of improving the quality of data transmission by reducing the rate of transmission errors for a given transmission power. It is recalled in this regard that the so-called “spatial diversity” technique consists in simultaneously transmitting one and the same message on one or more transmit antennas, and then in appropriately combining the respective signals received on each of the receive antennas.
It is recalled moreover that so-called OFDM modulation (the initials standing for “Orthogonal Frequency Division Multiplexing”) efficiently reduces the interference between data symbols. Moreover, OFDM is relatively fairly uncomplex to implement; in particular, OFDM signal modulation can be implemented in an efficient manner by means of an Inverse Fast Fourier Transform (IFFT), and the demodulation of an OFDM signal can be implemented in an efficient manner by means of a direct Fast Fourier Transform (FFT). However, OFDM modulation exhibits the drawback of being rather inefficient spectrally (because of the use of a “cyclic prefix”).
Another modulation, called “OFDM/OQAM”, has therefore been proposed which exhibits the advantage of being spectrally efficient (since it does not require any cyclic prefix, in contradistinction to OFDM), while circumventing (like OFDM) interference between symbols in a fairly uncomplex manner (the acronym OQAM stands for “Offset Quadrature Amplitude Modulation”).
In particular, the article by P. Siohan, C. Siclet, and N. Lacaille entitled “Analysis and Design of OFDM/OQAM Systems Based on Filterbank Theory” (IEEE Transactions on Signal Processing, vol. 50 No. 5, pages 1170 to 1183, May 2002) shows how it is also possible to implement OFDM/OQAM modulation by means of an IFFT and OFDM/OQAM demodulation by means of an FFT. Unfortunately, the technique presented in this article relates specifically to an SISO system, and does not therefore make it possible to benefit from the spatial diversity of SIMO/MIMO systems.